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October 9, 2008

3 Chemists Share Nobel for Fluorescent Protein Work

by Sam Savage

By Kenneth Chang

One Japanese and two American scientists have received the 2008 Nobel Prize in Chemistry for taking the ability of some jellyfish to glow green and transforming it into a ubiquitous tool of molecular biology to watch the dance of living cells and the proteins within them.

The new laureates are Osamu Shimomura, a Japanese-born emeritus professor at the Marine Biological Laboratory in Woods Hole, Massachusetts, and Boston University Medical School; Martin Chalfie, a professor of biological sciences at Columbia University, and Roger Tsien, a professor of pharmacology at the University of California, San Diego. They will each receive a one-third share of the 10 million krona prize, about $1.4 million, awarded by the Royal Swedish Academy of Sciences.

Tsien was not completely caught by surprise when the early morning phone call came Wednesday. Last week, the Thomson Reuters news service listed him among its predictions for this year's Nobel Prize laureates. "I didn't want to put any credence in it," Tsien said, noting that the predictions for the physics and medicine prizes this week were wrong.

"I can't pretend that it never crossed my mind," Tsien said, but added that his work was "only one little piece" among many researchers' work.

Biologists have long observed that some sea creatures glow in the dark. In 1962, Shimomura and Frank Johnson of Princeton isolated a specific glowing protein in a jellyfish that drifts in the ocean currents off the west coast of North America. The protein looked greenish under sunlight, yellowish under a light bulb and fluorescent green under ultraviolet light. Shimomura and Johnson called it the green protein, but nowadays it is known as green fluorescent protein, or GFP for short.

The green fluorescent protein consists of a chain of 238 amino acids bent into a cylindrical shape. Unlike other bioluminescent proteins, GFP does not require additives to glow.

Chalfie's group showed how the protein could be used as a biological identifier tag by inserting the gene that produces the protein into the DNA of an organism. In an early experiment, he inserted the protein into six cells of a transparent roundworm. When placed under ultraviolet light, those cells shined green, revealing their location.

By looking at mutations of the GFP protein, Tsien was able to make glowing proteins that were blue, not green, allowing biologists to track different cellular processes at the same time.

Biologists now routinely use green fluorescent proteins to track the growth and fate of specific cells like nerve cells damaged during Alzheimer's. The technique can even track specific proteins within cells.

In one experiment, the brain of a mouse was transformed into a kaleidoscope by tagging different nerve cells with different fluorescent proteins.

The protein has even entered the world of art. In 2000, Eduardo Kac, an artist, displayed a green glowing rabbit had been modified genetically with the GFP gene.